Not knowing some facts is not a reason for downvote, especially when author tried searching an answer and his question is well formed. Thanks for you answer though.
– ilyaigpetrovJul 30 '17 at 15:23

1

For what it's worth, this seems to be a decently fair question. It's a bit of a legal question, but I'm not worried about that.
– Zizouz212♦Jul 31 '17 at 3:51

3

What possible reason do you think you would be legally allowed to use someone else's copyrighted assets without permission??
– curiousdanniiJul 31 '17 at 3:54

@curiousdannii I don't use assets verbatim, I change them, so it is a derivative work and it's not always clear when derivative becomes a separate asset of its own. Also screenshot is like a photo and I'm not sure if every photo belongs to those whose assets are depicted on it.
– ilyaigpetrovJul 31 '17 at 18:31

Under no circumstance you can use somebody's copyright works without permission. Whether your project is open source or not don't matter.
– SmallChessAug 1 '17 at 1:40

1 Answer
1

Remixes will inevitably encounter legal problems when the whole or a
substantial part of the original material has been reproduced, copied,
communicated, adapted or performed – unless a permission has been
given in advance through a voluntary open content license like a
Creative Commons license, ...
Generally, the courts consider what will amount to a substantial part
by reference to its quality, as opposed to quantity and the importance
the part taken bears in relation to the work as whole.